Burning transuranium isotopes in thermal and fast reactors

Abstract

Energy production in nuclear power plants on the basis of fission processes lead inevitably to fission products and to the generation of new actinide isotopes. Most of these fission products are rather shortlived and decay within less than about 500 years to stable nuclides. However, a few of them, e.g. 99Tc and 129I, are longlived and may contribute to the radiotoxicity and hazard associated with an envisaged repository for their long-term disposal in a stable geologic formation, e.g. a salt dome. The majority of the generated actinide isotopes are fairly longlived, e.g. 239Pu with a halflife of more than 20 000 years. Therefore, their direct storage poses a heavy burden on the capacity and the possible environment impact of a repository. Furthermore, the energy content of these actinides could be deployed for producing additional nuclear fission energy after recovering them from unloaded irradiated fuel by suitable reprocessing techniques. Various possibilities exist for burning these actinides in different types of reactors, e.g. in light water reactors (LWRs), or LMFRs, adhering to available technology, or in actinide burners particularly designed for the purpose of their efficient incineration. The different options will be discussed in the paper. Transmutation of the manmade actinides and longlived fission products will require advanced technologies e.g. regarding reprocessing losses, remote fabrication techniques, and most probably, isotope separation processes. However, the almost complete elimination of these nuclides resulting from fission energy production in a continued recycling process may be the only feasible way to limit the effects of nuclear power generation to a tolerable and fair level for generations to come.